Propulsion system



Jan. 18, 1966 N. FAlrlcA PROPULSION SYSTEM Filed April 22, 1964 INVENTOR. /V/a/OL H5 FA? 77o@ gra/1k.

United States Patent O 3,229,462 PROPULSION SYSTEM Nicholas Fatica, Cleveland, Ohio, assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Apr. 22, 1964, Ser. No. 361,921 3 Claims. (Cl. titl-39.2)

This invention relates to a closed cycle propulsion system. More particularly, this invention pertains to a sennclosed torpedo propulsion system using aluminum as a source of hydrogen. n

An object of this invention is to provide an improved propulsion system of the closed cycle variety wherein the ratio of oxidizer to fuel is rendered substantially constant by a simplified system of control.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawing, wherein the figure is a flow plan of the process of this invention.

The trend in underwater propulsion systems in general and torpedo power plants, in particular, is towards higher speeds, longer range, and ability to operate at any depth without sacrificing performance. One of the best propulsion systems from this point of View involves the generation of hydrogen as a fuel for the system. However, the control aspect of such a system is important to the ultimate choice of a hydrogen generator for the system.

Of the control requirements, the most critical is lthe ability to maintain the mass ratio of hydrogen lto peroxide constant at all times in order to obtain a stoichiometrically balanced mixture of fuel and oxidizer. This mass .ratio must be kept as constant as possible in the face of variable power demands in order to prevent an excessive accumulation of non-condensables in what may be considered to be a practically closed system.

I have devised a process wherein the mixture of fuel and oxidizer may be maintained constant by metering the water input to each of the units concerned, i.e. fuel generator and oxidizer store, by means of a common displacement device. As illustrated, water is provided to unit 1, a hydrogen generator, and unit 2, a store of concentrated hydrogen peroxide, by two of three displacement pumps 3 and 4, each of which is mounted on a common shaft The peroxide displaced from unit 2 by the water is directed into a decomposition chamber 7 and the oxygen coming from the chamber and the hydrogen from unit .1 are both directed into a combustor 8. The hydrogen is then oxidized with the oxygen and sufficient diluent water is added to the combustor 8 by means of pump S in order to keep steam generated at reasonable temperatures. The steam coming from the combustor 8 drives a prime mover 9 and is condensed in unit 10, and part of it is returned to the units 1 and 2 and the combustor 8 by the displacement pumps 4, S and 6, and any non-condensables are driven off through a compressor 11.

Thus it may be seen from a perusal of the process described that I have invented a simplified system of control for a substantially closed cycle propulsion system. The metering of water to the three separate units controls the operation of the process and the metering of water is si- 3,229,462 Patented Jan. 18, 1966 ICC multaneously controlled by three separate displacement pumps, each of which is mounted on a common shaft.

In the past, the hydrogen output of unit 1, the generator, could not be controlled by the input of water because the ratio of fuel production to input of water was not constant. This was attributable to the fact that the usual hydrogen producing charge of the generator, for example, lithium hydride, formed both oxide and hydroxide compounds. Therefore, a basic requirement of the process was the substitution of aluminum as the basic charge of the generator. Aluminum reacting with water can also form the oxide and hydroxide. One might expect similar metering problems. However, the conditions for the formation of anything but the oxide are not likely to be encountered at any point in the generator. The hydroxide is unstable at temperatures above the boiling point of water under normal conditions and bed temperatures in the generator are far above this. Thus, in the production of hydrogen, aluminum will only forni the oxide compound and the ratio of hydrogen produced to input of water is constant and the control of fuel output by the generator may be accomplished indirectly by controlling the reactant water input.

The substitution of aluminum for say lithium hydride as a basic charge of the generator is also advantageous for other reasons as well. Thus on the basis of thermal energy per unit volume, the aluminum system has at least 50 to 90% more energy than a comparative system utilizing lithium hydride. Even on a weight basis, the aluminum system would be 7 to 13% superior to the comparative systems conventionally known. If the 1generator is considered only as a hydrogen source, with no heat recovery attempted, a generator packed with aluminum would yield 50% more hydrogen than one packed with lithium hydride. Under such conditions, the aluminumperoxide system would still yield 15% more energy per unit volume than the comparative system.

Also, the flow of hydrogen from unit 1 would be limited by the relief valve in the hydrogen line.. No hydrogen would flow until a pre-set pressure is reached. In practice the H2 generator is initially tilled with H2 to the preset pressure by water, released from a pressurized tank, reacting with a small quanity of sodium placed at the bottom of the aluminum charge. Thereafter, since the ratio of hydrogen produced to water input is constant, hydrogen and peroxide can be metered, the mass ratio between the two being kept constant by mounting the displacement pumps on a common shaft. The shaft speed controls each of the flows of water to units 1 and 2 and to combustor 8.

Although the temperature of the hydrogen as it leaves the generator will rise with time, the heat content of this stream will not aifect the temperature of the steam entering the turbine enough to justify temperature control. For example, a temperature rise of l000 F. of the hydrogen stream would increase the steam temperature by less than 5060 F., and this would only occur near the end of the run.

The relief valve in the hydrogen line is needed to prevent accumulation of either hydrogen or oxygen in the condenser when the speed is changed. Without such a valve, which serves to maintain constant pressure in the generator, hydrogen gas would accumulate in the free volume of the generator at startup. This would result in an oxygen excess in the condenser. If the system is being slowed down the hydrogen would continue to bleed from the generator resulting in an excess of hydrogen in the condenser.

Obviously, I have invented a closed cycle propulsion system having simplified controls. There will be many modifications and variations of the present system which will become apparent to one skilled in the art in View of the above teachings. Each and every one of these variations is to be rconsidered part of the present system. Therefore, it is to be understood that the invention as set forth in the appended claims may be practiced otherwise than as described.

I claim:

1. A substantially closed cycle propulsion system coma fuel generator, a store of oxidizer, a combustion chamber, a steam-driven prime mover, a condenser, three separate displacement pumps driven by a common drive shaft, a first of said pumps supplying and metering water to said fuel generator, a second of said pumps supplying and metering water to said store of oxidizer, and the third of said pumps supplying and metering diluent water to said combustion chamber to produce steam, said fuel generator and said store of oxidizer being connected to deliver fuel and oxidizer to said combustion chamber, said combustion chamber being connected to supply steam to said prime mover, said prime mover being connected to deliver exhaust steam to said condenser, and said condenser being connected to deliver water to said pumps. 2. The system of claim 1 wherein said fuel generator is a hydrogen generator containing a charge of aluminum.

3. The system of claim 1 wherein the speed of the common drive shaft is variable, whereby the power developed by the prime mover is controllable.

References Cited bythe Examiner UNITED STATES PATENTS 3,101,592 8/1963 Robertson 6039.05X

MARK NEWMAN, Primary Examiner. R. D. BLAKESLEE, Assistant Examiner. 

1. A SUBSTANTIALLY CLOSED CYCLE PROPULSION SYSTEM COMPRISING: A FUEL GENERATOR, A STORE OF OXIDIZER, A COMBUSTION CHAMBER, A STEAM-DRIVEN PRIME MOVER, A CONDENSER THREE SEPARATE DISPLACEMENT PUMPS DRIVEN BY A COMMON DRIVE SHAFT, A FIRST OF SAID PUMPS SUPPLYING AND METERING WATER TO SAID FUEL GENERATOR, A SECOND OF SAID PUMPS SUPPLYING AND METERING WATER TO SAID STORE OF OXIDIZER, AND A THIRD OF SAID PUMPS SUPPLYING AND METERING DILUENT WATER TO SAID COMBUSTION CHAMBER TO PRODUCE STEAM, SAID FUEL GENERATOR AND SAID STORE OF OXIDIZER BEING CONNECTED TO DELIVER FUEL AND OXIDIZER TO SAID COMBUSTION CHAMBER, SAID COMBUSTION CHAMBER BEING CONNECTED TO SUPPLY STEAM TO SAID PRIME MOVER, SAID PRIME MOVER BEING CONNECTED TO DELIVER EXHAUST STEAM TO SAID CONDENSER, AND SAID CONDENSER BEING CONNECTED TO DELIVER WATER TO SAID PUMPS. 